Characteristic parameters and development properties of air-gap discharge in oil-paper insulation

Oil-paper insulation system is the most common insulation method of high-voltage apparatus. As the event of air-gap discharge can lead to aging and disruption of the insulation system, awareness of emergence and development of air-gap discharge in time could be helpful in finding internal latent fault of oil-paper insulation system. The paper does research on the air-gap discharge in the oil-paper insulation, and uses kernel principal component analysis method to reduce the dimension of statistical parameters and to extract new characteristic parameters. The sample signals at different times during the development process of discharge are adopted to cluster the new characteristic parameters. The air-gap discharge development process can be divided into four stages according to the information generated at different periods of the process combined with the clustering results. The four stages can be defined as: incipient discharge, developing discharge, constant discharge, pre-breakdown.